The invention relates to an apparatus for determining tile flow of matter passing through a boundary surface.
Flow of matter or material flux in this context denotes a flow of particles, for instance, ions, molecules or gases, which passes through an interface or boundary between different media, or different phases of one medium, and whose intensity per unit of area and time is to be quantified, for example, in particles per second and square meter, or mol s.sup.-1 m.sup.-2.
If it is possible to determine particle concentration, partial gas pressure, etc., on both sides of an interface, the corresponding material flow may be inferred from the difference of the measured values. Problems arise if the necessary data cannot be obtained on one side of the interface, or if they are not accurate enough.